The present invention relates generally to an improved surgical tool for cutting and/or grasping food particles and/or human tissue, and more particularly to a tool of this type that utilizes a pair of cooperating jaw members that have a unique relative motion that offers significant advantages over known tools of this type.
As is well known, food particles (e.g. a piece of meat) sometimes become lodged in the esophagus while a person is eating, and this can become quite serious if the food particle is not removed promptly. One conventional tool presently used for this purpose includes a pair of cup shaped members mounted together with a scissors-like connection which allows the two cup shaped members to move apart and together with a pivotal movement, and the edges of the cup shaped members act as cutting edges when the two members come together. This tool is used by inserting it through an endoscope placed in the throat of the patient, and, using an operating cable extending to the tool, opening and closing the cup shaped members so that, with each such movement, a small piece of the food particle is cut away and retained with the lower cup shaped member, and the lodged particle of food is gradually reduced in size sufficiently that it can be easily dislodged.
This known device has several drawbacks. First, the conventional scissors-type pivot mounting between the cup shaped members inherently results in an ever decreasing closing force between the cup shaped members as they approach one another, with the smallest force being present at the point where the greatest force is required, namely at the point where the cup shaped members are almost in contact with one another and a portion of the food particle is being cut away. Additionally, the circular cutting edges of the cup shaped members is relatively inefficient in terms of a proper cutting action, and, as a result it is often necessary to make a large number of cutting strokes to remove a significant portion of the food particle. Finally, since the cup shaped members must be inserted through an endoscope placed in the esophagus of the patient, they must be small, and, as a result, the volume of the cup-shaped members is quite small and can only hold a limited amount of particles cut from the lodged food particle. Moreover, when the cup-shaped members are full, they must be removed and cleaned, often in the middle of a procedure.
In general, tools of the aforesaid type may also be used as a biopsy tool to remove a portion of a tumor or other human tissue for evaluation after it has been removed, and the above-described drawbacks of such tools are even more pronounced in biopsy applications. For example, if the tool is to be inserted into the body to remove a part of an internal tumor, it must be inserted through a hollow sheath that is small enough to be readily inserted into the body, and therefore the cup shaped member must be very small in size, which exacerbates the problem of having insufficient force to properly cut away a portion of a tumor at the point where the cup shaped members come together at the tumor.
Additionally, other tools of this general type have been proposed which include a pair of laterally extending jaw members that have a pivoted connection at one end of each of the jaw members, and that have some type of lost motion or similar connection that results in a cutting action between the jaw members. Some typical tools of this type are disclosed in U.S. Pat. Nos. 4,887,612; 5,496,347; 5,489,292; 5,556,407; 5,603,724; and 5,618,294. Wile these tools overcome some of the drawbacks of the above-described cup shaped member tool, the arrangement of the pivot connection and the lost motion connection is such that a major part of the closing force applied to the jaw members by the operating cable is lost, and the closing force applied to the jaws at the end of the cutting stroke, just as the jaws come together to begin cutting the food particle or the tumor, is at a minimum, even though it is at this point that the cutting force should be as large as possible. More specifically, in some of these prior art patents it is believed that because the pivot connection is located between the lost motion camming connection and the extending end of the jaw members, and, as a result, the fulcrum is located too close to the ends of the jaw members to effectively transmit and conserve the force manually applied to the operating cable by the user of the tool, only a minimum closing force is applied to the jaws when they come together at the point where the food particle or tumor is being cut by the jaws.
By contrast, the present invention provides a tool which maximizes the conservation of force at the point where cutting occurs, and provides significantly improved results as compared to known tools of the type described above.